Many gasoline and diesel cylinder head covers are isolated systems. The covers may be balanced between elastomeric isolator grommets and an elastomeric perimeter gasket. One approach to improve sealing capability is to increase the overall stiffness of the isolation system. However, increasing stiffness of the isolation system may increase Noise Vibration and Harshness (NVH) of the engine and/or cylinder head cover. Conversely, decreasing stiffness of the isolation system may increase the risk of oil leaks.
As one example compromise between sealing and stiffness, U.S. Pat. No. 6,371,073 to Billimack et al. discloses a cover member having a peripheral flange portion fixedly secured to an upstanding wall portion of an engine cylinder block. A sealing flange member is interposed between the peripheral flange and the upstanding wall portion. In addition, an isolation member, fabricated from an elastomeric material, is interposed between the sealing flange member and the peripheral flange. The three piece assembly, i.e. the peripheral flange portion, the isolation member, and the sealing flange member, is then secured to the upstanding wall portion with a plurality of bolts.
However, the inventors herein have recognized several issues with such an approach. As one example, the approach requires the addition of an upstanding wall portion to be added to the surface of the engine block, which may increase manufacturing costs, and affect the vibration characteristics of the engine block.
Thus, in one example, the above issues may be addressed by a cylinder head cover for an internal combustion engine wherein the sealing function and the NVH isolation function are decoupled from one another. The cylinder head cover may include a bottom carrier having a first end configured to be disposed in sealing engagement with a cylinder head. The bottom carrier may also have a second end. A cover body may be configured to provide a covering surface, and may have a side wall extending toward the cylinder head. A resilient joining element may connect the bottom carrier second end to an edge of the cover body side wall in sealing engagement.
The bottom carrier may serve to seal the cylinder head cover at a juncture between the cylinder head and the bottom carrier first end. By connecting the bottom carrier to the edge of the cover body at the second end of the bottom carrier, i.e. spaced from the first end, the sealing function and the NVH isolation function may be separated, and may be individually optimized. Further the joining member may serve to provide both a portion of the covering function of the cylinder head cover, and at least a portion of the NVH isolation functionality. In this way an efficient, and cost effective, structure may be provided.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.